Concrete block making machine



Oct. 22, 1940. R w PFEKFER 2,218,767

CONCRETE BLOCK MAKING MACHINE Filed April 27, 1936 6 Sheets-Sheet l INVENTOR. EYEQEHMX WEZZFEH ATTORNEY.

Oct. 22, "1940. F. w. PFEIFER CONCRETE BLOCK MAKING MACHINE Filed April 27, 1956 '6 Sheets-Sheet 2 ATTORNEY.

oct. 22, 1940 w, PFElFER 2,218,767

CONCRETE BLOCK MAKING MACHINE Filed April 27, 1956 6 Sheets-Sheet 3 ATTORNEY.

Oct. 22, 1940. F, w PFE|FER 2,218,767

CONCRETE BLOCK MAKING MACHINE Filed April 27, 1936 6 Sheets-Sheet 4 VIIIIIII/IIIIIIIII/lll IIIIIIIIIIIIIIIIIIII/l INVENTOR. FEEDER/5K WB IJFER ATTORNEY.

Oct- 22, 1940. F. w. PFEIFER CONCRETE BLOCK MAKING MACHINE Filed April 27, 1936 6 Sheets-Sheet 5 lllll NW E.

INVENTOR. .FEEZ/EEZZK WHEJFEH V BY g My 5% ATTORNEY.

Oct. 22, 1940. F. w. PFEIFER CONCRETE BLOCK MAKING MACHINE Filed April 27, 1936 6 Sheets-Sheet 6 I INVENTOR. FYE'DERMK WfiEJPEE ATTORNEY.

Patented Oct. 22, 1940 UNITED STATES PATENT OFFICE concas'm BLOCK MAKING mom Frederick W. Pfeil'er, West Allis, Wis. Application April 27, 1936., Serial No. 76,642

31 Claims.

This invention relates to a method of manufacturing concrete building blocks, and to amachine for practicing the method.

In attempts to manufacture concrete blocks from light weight material such as slag or cinder concrete, it has been common practice to tamp or press the material in the mold. Such tamping fractures the light, porous aggregate in the concrete adjacent the tamper. The surfaces fractured are not coated with cement, and hence are not cemented together when the concrete sets. The result is that if the blows of the tamper are severe enough ,to properly tamp the concrete at the bottom of the mold, the concrete at the top will be so fractured as to crumble readily. If less pressure is exerted in the tamping, that portion of the block adjacent the tamper is well tamped, but the density of the block diminishes as the distance from the tamper increases. The result of lighttamping is, therefore, a block which is properly tamped adjacent the tamper but which has other parts soft and crumbly.

The present invention has as one object the production of a light weight concrete block of even texture.

Another object is to devise a method of forming light weight concrete blocks in which breakage of the fragile aggregate is avoided.

Another object is to devise a method of forming light weight 'concrete blocks in which all parts of the blocks are subjected to substantially the same tamping pressure.

A further object is to produce a machine to form blocks of light weight concrete which will exert a uniform tamping pressure throughout the depth of the blocks.

A further object is to produce a machine to form blocks of light weight concrete having even texture.

A further object is to produce a block forming machine which will mold light weight concrete blocks without breaking the aggregate during molding. v

A further object is to produce a block forming ing of the concrete is done by vibration, and in which the concrete is maintained above the top surface of the block during the forming operation.

Another object of the invention is to produce a machine to form light weight concrete blocks with holes therethrcugh, the machine including an improved core mounting and actuating mechanism. 55 A still further object is to produce a block machine to mold concrete blocks in which pack-' forming machine to mold light weight concrete blocks in whiohexcess material is removed from the top of the block after suitable tamping and is used in the formation of the next block.

The method of forming light weight concrete 5 blocks comprises, filling a block mold with COD: crete, maintaining the level of the concrete above the top of the mold, and subjecting the mold and concrete to vibration to tamp the concrete.

The machine used to accomplish this method 10 includes a mold mounted on a vibrating table,

and a hopper above the mold adapted to vibrate therewith while maintaining the minimum level of the concrete above the top of the mold.

The invention further comprises, in combina- 15 tion with the jarring table and the mold, cores which project horizontally into the molds through the vertical ends of the molds.

' The invention also comprises a pair of knives which are adapted to pass between the mold and 20 the hopper to cut oil the concrete at the top of the mold and form a bottom for the hopper.

A specific example of such a machine is shown in the accompanying drawings and described in the following specification. In the drawings:

Fig. 1 is a front elevation of the machine with the cores in place;

Fig. 2 is a top view of the machine with the cores withdrawn;

Fig. 3 is a horizontal section through the mold 39 with the cores in place;

Fig. 4 is an end view of the machine with the hoppers in raised position and the molds on their sides, preparatory to removing blocks from the molds; 35

Fig. 5 is a cross-section on the line 55 of Fig.

2, with the molds in working position and the hoppers raised;

Fig. 6 is a cross-section on the line 6-6 of Fig. 2, showing the cores withdrawn from the 40 molds;

Fig. 'I is'a detail showing the cradles for carrying the hoppers and the cut-off knives;

Fig. 8 is a cross-section on the line 8-8 of Fig. 5, loolcing in the direction of the arrows; and

Fig. 9 is a detail of the cradle latch and release.

Referring to the drawings, in which like numerals indicate like pants throughout the several views, the machine is built on a frame generally designated l5, which may comprise a base 16, four posts I1, and suitable cross braces it between the posts.

The base 16 includes a pair of I-beams 2O which support a cylinder jacket 2|. The Jacket 2| has a vent port 22 to permit the escape of air therefrom. A cylinder 23 is mounted within the jacket 2|. A piston 24 operates in the cylinder 23, and has an extension or collar 25 of enlarged diameter which rests on the top of the jacket 2| to prevent the bottom of the piston from striking the bottom of the cylinder.

An air conduit 26 is formedin the piston and leads from a valve-controlled air hose 2'! through the collar 25 to a point on the side of the piston adjacent the side wall 01' the cylinder 23. When the piston is in its lowermost position, as shown in Fig. 6, the lower end of the conduit 26 opens into a conduit 28 in the side of the cylinder 23, which, in turn opens into the space below the piston. A port 26 vents the compressed air trapped below the piston when the piston rises above the port.

The lower end of the piston is recessed to trap a comparatively large quantity of compressed air before the piston 24 has time to move the conduits 26 and 28 out of engagement. Thus uously to give a jolting or vibrating table for tamping the concrete.

The piston 24 car-111% a table 35 which may either be cast solidly with the piston or formed separately and attached to the piston. The table carries a pair of molds 36, one on each of the machine. The molds are pivoted to the table by hinges 31, which permit the molds to swing from a normally vertical position in which the blocks are formed, shown in Fig. 5, to a reclined position in which the molds rest on bracket-s 38 on the frame l6. shown in Fig. 4. In the horizontal position the completed blocks may be removed from the forms or molds 36 and prefera-bly placed in a drier.

The frame l has a frame 46 mounted on each side thereof at approximately the level of the table 35. As shown in Figs. 3, 4 and 6 the frames 46 support horizontal angle irons 42, which carry tracks 43. The tracks 43 guide a carriage 45, which is held on the tracks by a T-bar 46 hearing on the top of the carriage. Each carriage 45 has a pair of vertical posts 41 which carry one end of a core frame 49.

The core frame 49 has a guide 56 which operates on a track 5! fixed to the table 35. The outer end of the frame 49 comprises a vertical member which carries brackets 52. The brackets 52 embrace the posts 41 and slide thereon through a distance slightly greater than the stroke of the piston 24. When the table 35 is in its lowermost position the guide 56 is horizontal.

The frames 49 carry cores 55 which fit through corresponding holes 56 in the ends of the molds 36 as shown in Fig. 3. It will be noted that the guides 56 are slightly longer than the cores 55, which enables the cores to be completely withdrawn from the molds 36 while maintaining the guides 56 on the tracks 5i. As shown in Fig. 3, the carriage 43 on one side of the frame rides on one pair of parallel tracks 5i while the carr ge 46 on the opposite side of the frame rides on an adjacent pair of parallel tracks 5|.

The entire carriage 48, including the cores 55, vibrates with the table 36, entirely independently of the carriage 45.

The cores 55 are moved to and from their positlon in the molds 38 by fluid motors 59 each of which comprises a. cylinder 66 closed at both ends, with a pitson 6| operating therein. The pistons have piston rods 62 which pass through packings in the outer ends of the cylinder and are connected to the carriages 45 in any suitable manner. The fluid motors 56 may be operated by the same air pressure source that operates the vibrator piston 24. The flow of air pressure to either side of the piston 6| is controlled by a valve on the frontof the machine.

The molds 36 are filled with concrete through a pair of hoppers 65 mounted one above each mold. The hoppers are connected by two bars 61 one at each end of the hoppers. A guide 68 composed of two angles back to back is mounted on each end of each hopper and operates on a. track 16 to guide both hoppers simultaneously onto or away from the molds 36.

Deflectors TH are mounted longitudinally in the hoppers to prevent the concrete from falling directly onto the cores 55 and bending them.

The hoppers are carried within a cradle, generally designated 15 and best shown in Fig. 7, which has four parallel guides I6 each of which is composed preferably of a pair of angles back to back which guide the cradle in its vertical movement on tracks TI fixed in the frame [5. The guides 16 are joined adjacent the top by cross members '|8'l8. At the bottom of the cradle are a pair of angles 16 which run perpendicularly to the length of the hoppers, and which are adapted to engage the cross pieces 61 joining the hoppers to raise the hoppers with the cradle. Suitable angles 86 join the angles 19 to complete the cradle. In its lowermost position the cradle 75 rests on a. cross bar 8| which may be adjusted in elevation by the bolts 82.

A pair of knives 83 are mounted in the cradle and lie on top of the inwardly projecting leg 84 of the angle 19. The knives are adapted to be moved outwardly between the molds 36 and the hoppers 65 to cut off the concrete above the top of the molds prior to withdrawing the hoppers from the molds.

The knives 83 are each operated by a pair of racks 85 which are fixed to the knives and are engaged by pinions 86-86 or 81-81. It will be noted that the pinions 86-86 have a blank circumference intermediate the ends of the pinions in which there are no pinion teeth to permit the racks not actuated by that pinion to pass freely under it.

Both the pinions 86-86 and 81-81 are operated by double faced rack bars 96 in such a manner that when the bars are drawn up, the knives 83 are forced out to cut off the concrete between the hoppers and the molds.

Each of the rack bars 96 is guided by a pair of angles 9l--6| back to back which are fastened to the frame l5. A filler 62 is fixed between each pair-of angles 9|-9| to hold the rack bar at the proper distance from the frame 15. The rack bars 96 pass through holes in the angle 76 and are provided with lugs 93 at the lower ends, adapted to engage the angle '19 on the up stroke of the bar 96 and raise the cradle.

The rack bars are connected together by a pair of bars 94 and braced by diagonal braces 95, as shown in Fig. 6.

A'motcr 96 which may be operated by compressed air is connected to the bars 94 through the piston rod 91 to raise the rack bars 99 and so force the knives outward and cut off the concrete at the top of the molds and then raise both the cradle and the hoppers off the molds.

A latch 98, best shown in Fig. 9, is provided in order to prevent the motor 99 from raising the hoppers before the knives 83 have completely out off the concrete at the top of the molds. This latch is fixed in the frame 15 and includes a spring pressed plunger 99 which has a projection I99 with a cam surface l9l thereon. A cam follower I92 is provided on the bottom of the rack bar 99 to disengage the plunger 99 from its recess in the angle 19 when the knives 83 are in their outermost position.

Operation In operation, the molds 36 are moved into upright position with the front plates clamped thereon. Compressed air is then admitted-to the outer ends of the cylinders 69 to move both the pistons 6| and the carriages 45 inwardly and insert the cores 55 through the apertures 56 and into place in the molds 36.

After the cores 55 are in place fluid pressure is admitted to the top of the fluid motor 96 to lower the double rack bars 99. The bars 99 lower the cradle 15 onto the cradle support 8| at which time the hoppers rest on the tops of the molds 36, with the knives 83 covering the bottoms of the hoppers to prevent the passage of concrete into the molds.

Further downward movement of the rack bars 99 operates the pinions 86 and 81 which arcuate the rack bars 85. and draw the knives 83 inwardly onto the cradle 15 and thus open the bottoms of the hoppers 65 and permit the concrete in the hoppers to move down into the molds. Additional concrete is supplied to the hoppers from any convenient source, preferably through a stationary supply hopper (not shown).

While concrete is being supplied to the molds 36 through the hoppers 65, air pressure is admitted' throughthe hose 21 to the vibrator cylinder 23 .to cause the table to vibrate or jolt in a manner heretofore described. The table 35 carries both the molds 36 and-the hoppers 65 which vibrate with the table 35.

When the knives are withdrawn from the hoppers 65 onto the cradle 15, the hoppers are free to vibrate with the molds 36 independently of the knives 83 which remain stationary during the vibration of the table.

The vibration or jolting of the molds 36 and the hoppers 65 tamps the concrete and forms it into a dense compact mass.

During the jolting or vibrating process concrete is kept in the hoppers 65 above the tops of the molds 36. The height at which the concrete must be maintained above the tops of the molds is determined by the weight and consistency of the concrete and by the distance through which the table drops, or the severity of the jolting.

The concrete must be as dry as possible in order that the blocks may be removed from the molds as soon as the jolting is completed. Any mechanical tamping of such dry concrete affects only the portion adjacent the tamper, and the effect of the tamping tapers off rapidly as the distance from the tamper increases. When such concrete is jolted the weight of each particle of concrete forms a tamper for the concrete beneath it. Since tamping affects only the concrete fora comparatively short distance below the tamper, when the concrete is jolted the tamping effect builds up to a maximum as the head increases and remains constant for the remainder of the depth of the block.

The minimum height at which the concrete is maintained above the tops of the molds is, therefore, the height of concrete required to give the maximum or uniform tamping effect for the particular concrete and jolting conditions. A smaller head or height of concrete produces a block improperly tamped adjacent the top. A greater head, on the other hand, has no effect other than to thoroughly tamp the concrete in the bottom of the hopper 65.

When the concrete is thoroughly tamped the vibration is stopped by manually cutting of! the air supply to the vibrator 23-24. Air is then admitted to the lower side of the fluid motor which raises the doublerack bars 99. Durin the raising of the rack bars 99, the cradle 15 is prevented from moving by the locks 98 which hold the cradle in its lowermost position until released by the cam followers I92.

The rack bars 99 turn pinions .86 and 81 which push the knives 83 outwardly, as best shown in Fig. 8, and cut off the excess concrete at the tops of the molds.

When the knives 83 are in their outermost position, the cam followers I92 release the latches 98, and the lugs 93 engage the angles 19 and lift the cradle 15. The tops of the angles 19 engage the bars 61 joining the hoppers 65 and move the hoppers up with the cradle 15.

The cores 55 may be withdrawn from the molds after the knives have cut off the concrete at the tops of the molds. The cores are withdrawn by supplying air to the inner ends of the cylinders 69, which moves out the pistons 6| and carriages 45 and 49 and withdraws the cores.

The molds 36 may then be turned down to a horizontal position, in which they rest on the brackets 38. The side of the mold resting on'the bracket 38 is then released and the remainder of the mold 36 is moved away from the released side and returned to its normal vertical position.

The finished block which rests on the released side plate is removed therewith and preferably placed in a drier until cured. A new side is clamped in place on the mold and the cycle repeated.

It will be apparent that this invention is susceptible to various changes and modifications, and it is not, therefore, desired to limit it to the precise form herein shown and described but only by the scope of the appended claims.

What is claimed as new and desired to secure by Letters Patent is:

l. A machine for molding concrete blocks or the like, comprising, a frame, a vibrator mounted in said frame, a table mounted in said frame and adapted to be vibrated by the vibrator, a

mold pivotally mounted'on said table to vibrate therewith, said mold being rotatable with the finished block from a vertical molding position to a horizontal position in which the finished block may be removed, a feed hopper mounted in said frame and adapted to rest on said mold when in vertical position to vibrate therewith and to raise above said mold to permit the mold to pivot to horizontal position, means mounted on said frame to raise the hopper while permitting the hopper to vibrate independently of the said means, and a knife carried by said means to cut oif concrete at the top of the mold.

2. A machine for molding concrete blocks or the like, comprising, a frame, a vibrator mounted in said frame, a table mounted on said vibrator and adapted to be vibrated thereby, a mold carried by said table and vibrated therewith, a feed hopper mounted over said mold adapted to feed concrete into the mold, a cradle mounted in said frame independently of the vibrating portions of the machine, a knife mountedin said cradle and movable to a position between the mold and the hopper to sever the concrete therebetween, and means mounted in the frame to operate said knife.

3. A machine for making concrete blocks or the like, comprising, a frame, a vibrator mounted in said frame, a table carried in said frame and adapted to be vibrated by said vibrator, a mold pivotally mounted on said table to vibrate therewith, said mold being open on the top and rotatable on its pivot from its normal vertical position to a horizontal position, a feed hopper movably mounted in said frame adapted to vibrate with said mold and to move from a posiiion on said mold to a position which will permit the mold to swing to its horizontal position, a cradle movably mounted in said frame engageable with the hopper to move the same off the mold, a knife carried in said cradle and movable to sever the concrete between the feed hopper and the mold, means to operate said knife, and means on said last named means engageable with said cradle to move said cradle and said hopper.

4. A machine for making concrete blocks or the like, comprising, a frame, a vibrator mounted in said frame, a table carried in said frame and adapted to be vibrated by said vibrator, a mold mounted on said table to be vibrated therewith, said mold having apertures therein to admit a core, a bracket mounted on said frame, a carriage movable on said bracket, a second carriage movable on said table, means connecting said carriages to permit vertical movement of said second carriage relative to the first, a core carried by said second carriage, and means to actuate said carriages to insert and withdraw the core from the mold.

5. A machine for making concrete blocks or the like, comprising, a frame, a vibrator mounted in said frame, a. table carried in said frame and adapted to be vibrated by said vibrator, a mold carried by said table to vibrate therewith, a hopper mounted for movement onto and off said mold and adapted, when on said mold, to vibrate therewith, a cradle mounted to move in said frame independently of the vibrating members, means to move said cradle, and means on said cradle engageable with means on the hopper to raise and lower the hopper onto the mold.

6. A machine to mold concrete blocks, or the like, comprising, a frame, a vibrator mounted in said frame, a table mounted above said vibrator and adapted to be vibrated thereby, a

mold pivotally mounted on said table to vibrate therewith when in vertical position and to pivot to a horizontal position in which the finished block may be removed, a hopper mounted to move vertically in said frame and to rest on said mold and be vibrated thereby, and to raise off said mold to permit the latter to pivot to its horizontal position, and means to operate said hopper.

7. A machine to, mold concrete blocks, or the like, as defined in claim 6 in which the last named means comprises a cradle mounted in said frame.

8. A machine to mold concrete blocks, or the like, comprising, a frame, a mold mounted in said frame, means in said frame to vibrate the mold independently of the frame, a cradle movable in said frame, a hopper mounted for movement onto and off said mold, means on said cradle engageable with means on the hopper to raise the hopper off the mold while'permitting the hopper to vibrate independently of the cradle, and means to operate said cradle.

9. A machine to mold concrete blocks, or the like, as recited in claim 8, including a cut-ofi knife mounted in said cradle and operable upon conclusion of the vibration to sever the concrete between the mold and the hopper.

10. In a machine to make concrete blocks, or

the like, a frame, a vibrator mounted in said' frame, a mold mounted in said frame and adapted to be vibrated by said vibrator, a bracket mounted on said frame, a carriage mounted on said bracket, a plurality of cores adapted to move into and out of said mold, and means connecting said cores to said carriage, said means permitting the cores to vibrate with the mold independently of the carriage.

11. In a machine to make concrete blocks, or the like, a frame, a vibrator mounted in said frame, a mold mounted in said frame to be vibrated by said vibrator, a hopper mounted in said frame adapted to vibrate with said mold, a cradle mounted in said frame, means on said cradle engageable with means on the hopper to move the latter off the mold, a cut-off knife mounted in said cradle and adapted to sever the concrete between the hopper and the mold, means to actuate said knife, and means on said last named means engageable with the cradle to lift the latter.

12. A machine as recited in claim -11, including a lock mounted in said frame and engageable with said cradle to retain the cradle in its lowermost position until the knife has severed the concrete between the mold and the hopper.

13. A machine as recited in claim 11, including a lock mounted in said frame and engageable with said cradle to maintain the cradle in its lowermost position, and means mounted on said last named means to release the look after the concrete has been severed between the hopper and the mold.

14. A machine as defined in claim 11, including a lock mounted in said frame and engageable with said cradle to maintain the cradle in its lowermost position, and a cam surface on said last named means engageable with said lock to release the cradle afterthe knife has completely severed the concrete between the mold and the hopper.

15. A machine to mold concrete blocks or the like, comprising, a frame, a table supported in said frame and adapted to vibrate therein, means to vibrate said table, a mold mounted on said table to vibrate therewith, a feed hopper mounted for movement onto and off said mold, and adapted to vibrate freely therewith when on said mold, a cut-off knife mounted in said frame independently of the vibrating portion thereof and adapted to cut off the concrete at the top of the mold after the block is formed, and means, including said knife to raise said hopper and the excess concrete therein off said mold.

like, comprising, a frame, a table supported in said frame and adapted to vibrate therein, means to vibrate said table, a mold mounted on said table to vibrate therewith, a feed hopper mount- ,ed for movement onto and off said mold, and adapted to vibrate freely therewith when on said mold, a cut-off knife mounted in said frame and adapted to cut off the concrete at the top of the mold after the block is formed, and means, including said knife to raise said hopper and the excess concrete therein off said mold I 17. A machine for making concrete blocks or the like, comprising, a frame, a vibrator mounted in said frame, a table carried in said frame and adapted to be vibrated by said vibrator, a mold having an aperture therein mounted on said table to vibrate therewith, a feed hopper mounted above said mold to vibrate therewith, a bracket mounted on said frame, a carriage mounted on said bracket, a second carriage movable on said table, means connecting said carriages to permit vertical movement of said second carriage relative to the first carriage, a core carried by said second carriage, and means to actuate said carriages to insert the core into the mold 7 through the aperture therein.

18. A machine for making concrete blocks or the like, comprising, a frame, a vibrator mounted in said frame, a table carried in said frame and adapted to be vibrated by said vibrator, a mold having an aperture therein mounted on said table to vibrate therewith, a feed hopper mounted above said mold to vibrate'therewith, a knife carried in said frame and insertable between the hopper and the mold to sever the concrete therebetween, a bracket mounted on said frame, a carriage mounted on said bracket, a second carriage movable on said table, means connecting said carriages to permit vertical movement of said second carriage relative to the first carriage, a core carried by said second carriage, and means to actuate said carriages to insert the core into the mold through the aperture therein.

19. A machine for making concrete blocks or the like, comprising, a frame, a vibrator mounted in said frame, a table carried in said frame and adapted to be vibrated by said vibrator, a. mold having an aperture therein mounted on said table to vibrate therewith, a feed hopper' mounted above said mold to vibrate therewith, a knife carried in said frame and insertable between the hopper and the mold to sever the concrete therebetween, means, including said knife, to raise the hopper and the excess concrete therein off the mold, a bracket mounted on said frame, a carriage mounted on said bracket, a second carriage movable on said table, means connecting said carriages to permit vertical movement of said second carriage relative to the first carriage, a core carried by said second carriage, and means to actuate said carriages to insert the core into the mold through the aperture therein.

20. A machine for making concrete blocks or the like, comprising, a frame, a vibrator mounted in said frame, .a table carried in said frame and adapted to be vibrated by said vibrator, a mold carried by said table to vibrate therewith, a hopper mounted for movement onto and off said mold and adapted, when on said mold, to vibrate therewith, a cradle mounted in said frame independent of the vibrating portions of the machine, a knife carried by said cradle and adapted to pass between the hopper and the mold to sever the concrete therebetween, means to move said cradle, and means on said cradle including said knife engageable with said hopper to raise the hopper and the excess concrete therein.

21. A machine for making concrete blocks or the like, comprising, a frame, a vibrator mounted in said frame, a table carried in said frame and adapted to be vibrated by said vibrator, a mold carried by said table to vibrate therewith, a hopper mounted for movement onto and off said mold and adapted, when on said mold, to vibrate therewith, a cradle mounted in said frame independently of the vibrating members, a knife mounted in said cradle, means to actuate said knife to cut off the concrete at the top of the mold, and means on said last named means to raise the cradle and hopper.

22. A machine as defined in claim 21 including means to hold the cradle in its lowermost position until after the knife has completely severed the concrete.

23. A machine for making concrete blocks or the like, comprising, a frame, a vibrator mounted in said frame, a table carried in said frame and adapted to be vibrated by said vibrator, a mold mounted on said table to vibrate therewith, a feed hopper movably mounted in said frame adapted to vibrate with said mold, a cradle movably mounted in said frame engageable with the hopper to move the same off the mold, a knife carried in said cradle and movable to sever the concrete between the feed hopper and the mold, means to operate said knife, and means on said last named means engageable with said cradle to move said cradle and said hopper.

24. A machine for making concrete blocks or the like, comprising, a frame, a mold mounted in said frame, a hopper movable onto and off said mold, a cradle engageable with a portion of said hopper to 'lift the hopper off the'mold, a knife mounted in said cradle, means to operate said knife to cut off the concrete between the mold and the hopper, a latch engageable with a portion of said cradle, and means to release said latch to permit the cradle to rise after the knife has completely severed the concrete between the hopper andthe mold.

25. A machine for making concrete blocks or the like comprising, a frame, a mold mounted in said frame, a hopper movable onto and off said mold, a cradle engageable with a portion of said hopper to lift the hopper off the mold, a knife mounted in said cradle, a rack bar. fixed on said knife, a pinion engageable with said rack bar, a second rack bar mounted substantially vertically and engageable with said pinion to actuate said knife, said rack bars and said pinion being so arranged that upward movement of the second rack bar moves the knife outwardly to sever theconcrete between the hopper and the mold, a latch engageable with a portion of said, cradle, andme'ans on said second rack bar to disengage said latch and permit the cradle to be raised after the knife has completely severed the concrete betweenthe mold and the hopper.

26. A machine for making concrete blocks or the like comprising, a, frame, amold mounted in said frame, a hopper movable onto and off said mold, a cradle engageable with a portion of said hopper to lift the hopper off the mold, a knife mounted in said cradle, a rack bar fixed on said knife, a pinion engageable with said rack bar, a second rack bar mounted substantially vertically and engageable with said pinion to actuate said knife, said rack bars and said pinion being so arranged that upward movement of mold, a cradle engageable with a portion of said hopper to lift the hopper off the mold, a knife mounted in said cradle, a rack bar fixed on said knife, a pinion engageable with said rack bar, a second rack bar mounted substantially vertically and engageable with said pinion to actuate said knife, said rack bars and said pinion being so arranged that upward movement of the second rack bar moves the knife outwardly to sever the concrete between the hopper and the mold, a latch engageable with a portion of said cradle, means on said second rack bar to disengage said latch, and a member formed on said second rack bar engageable with said cradle after reelase of said latch to raise the cradle.

28. A machine for making concrete blocks or the like comprising, a frame, a mold mounted in said frame, a hopper movable onto and off said mold, a cradle engageable with a portion of said hopper to lift the hopper oil the mold, a knife mounted for horizontal movement in said cradle, a pair of horizontal rack bars, one of said rack bars being fixed an each end of said knife, a pair of pinions mounted in said cradle and engageable with said rack bars, a second pair of rack bars mounted for substantially vertical movement in said frame and engageable with said pinions to actuate the knife outwardly upon upward movement thereof to sever the concrete between the hopper and the mold, means to actuate said second pair of rack .bars simultaneously, a latch engageable with a portion of the cradle, and means on one of said rack cars to disengage said latch and permit the cradle to be raised after the knife has completely severed in said frame, a hopper movable onto and off aaisnev said mold, a cradle engageable with a portion of said hopper to lift the hopper off the mold, a knife mounted for horizontal movement in said cradle, a pair of horizontal rack bars, one of said rack bars being fixed on each end of said knife, a pair of pinions mounted in said cradle and engageable with said rack bars, a second pair of rack bars mounted for substantially vertical movement in said frame and engageable with said pinions to actuatethe knife outwardly upon upward movement thereof to sever the concrete between the hopper and the mold, means to actuate said second pair of rack bars simultaneously, a latch engageable with a. portion of the cradle, means on one of said rack bars to disengage said latch and permit the cradle to be raised after the knife has completely severed the concrete between the hopper and the mold, and means on each of said second rack bars engageable with said cradle after said last named means has released said latch to raise said cradle.

30. A machine for making concrete blocks or the like comprising, a frame, a mold mounted in said frame, a hopper mounted in said frame and movable onto and off said mold, a cradle engageable with a portion of said hopper to lift the same off the mold, a knife mounted in the cradle, means to actuate the knife to cut off the concrete between the mold and the hopper, a latch engageable with a portion of said cradle when in lowered position, and means onthe knife actuating means engageable with said latch after the knife has completed the out between the hopper and the mold to release the latch and permit the cradle to raise the hopper off the mold.

31. A machine for making concrete blocks or the like comprising, a frame, a mold mounted in said frame, a hopper movable onto and off said mold, a cradle engageable with a portion of said hopper to lift the hopper off the mold, a knife mounted in said cradle, means to operate said knife to cut off the concrete between the hopper and the mold, a latch engageable with a portion of said cradle when in lowered position,

,means on the knife actuating means to release said latch after said knife has completely severed the concrete between the hopper and the mold, and means on said knife actuating means to raise the cradle after the release of the latch.

FREDERICK W. PFEIEER. 

